Isochronizing and synchronizing system



Dec. l, 1925- A. M. CURTlS lsOCHRONIZING AND SYNCHRONIZING SYSTEM FiledJune '13. 1923 2 Sheets-Sheet 1 Q Rs a, DJHUIIHIIUIIHIIUIIIE l /27Ven/0f." Ausf/'f7 M. Car/is by Af/y Dec. 1, 1925. 1,563,727

A. M. CURTIS l -ISOCHRONIZING vAND SYNCHRONIZING SYSTEM Filed June 13.1923 2 sheets-sheet 2 I L/ZO 7# /7 //7 Ven/0r." AUS/fn M Cw//S PatentedDec. 1, 1925.

treo sr'rs AUSTEN 1li. CURTIS, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TGWESTERN ELEC- 'ERIC COMPANY, INCORPORATED, O' NEW YORK, N. Y.,(J0RPOPtAONl F NEW YORK.

ISOCBRONIZING AND SYNCHRONIZING SYSTEM.

Application led June 13, 1923. Serial No. ld.

To all whom t may' concern:

Be it known that l, AUSTEN M. CUR'rs, a citizen of the United States,residing at East Orange7 in the county ot Essex., State of New Jersey,have invented certain new vand useful improvements in lsochronizing andSynchronizing Systems, of which the .following is a full, clear,concise, and exact description.y

This invention relates to isochronizing and synchronizing systems andparticularly to such. systems for use with high speed multiplextelegraph systems.

ln order to maintain synchronism between the distributors at distantstations of a multiplex telegraph system, it is customary to takeadvantage ot' the fact that the rate ot vibration ot' an electricallydriven tuning' fork which in turn drives the distributors, can bechanged slightly by changing its amplitude of vibration. A reduction inthe amplitude of vibration of the fork results in an increase in therate of vibration and conversely an increase in the amplitude ofvibration causes a reduction in the rate of vibration. The adjustment ofthe driving contacts also affects the degree of change in rate otvibration and it has been found that in some systems the rate of changeof frequency is not the same when the fork driving circuit is changed todecrease the frequency as when it is changed to increase the frequencyof the tuning fork. Varia tions in frequency are also caused byvariations in contact pressure and chatterin of the contacts, each ofwhich changes the riving force. Although this irregularity in thefrequency of vibration of the fork and its rate of change of frequencycauses a slight variation in phase between the distributors at thedistant stations, it is not ot suicient magnitude to preventsatisfactory operation of the ordinary low speed multiplex telegraphsystem. However, in high speed multiplex systems the distributors mustbe maintained in more exact syn chronisrn in order to insuresatisfactory operation. lThis has been Jfound to be particularly truefor systems used with long in ductively loaded submarine cables in whichcase economical use requires that the speed ot transmission be raised toa value several ,times that of the ordinary multiplex systern. rEhespeed obtainable with a multiplex system over such a cable may dependnearly as much on the exactness of synchronism maintained as it does onthe characteristics of the cable.

The object of the present invention is to enable high speedsynchronization to be obtained with more exact synchronisrn than hasbeen possible heretofore, and a higher rate of change of frequency thanin the systems used at present.

lt is a further object in such systems to substantially reduceanydiliculty due to sparking at the contacts causing Contact trouble andthe radiation of high frequency waves and to maintain a constant speedof operation.

To attain the main objects the invention contemplates a synchronizingsystem in which the tuning forks em yloyed to drive the distributors atthe stations are regeneratively driven and by the use ot sharply tunedelectric circuits may be maintained at the desired frequency within veryclose limits. By changing the tuning ot the driv-y ing circuit at thecontrolled station, the speed ot vibration of the tuning rorlr at thatstation is corrected when necessary so as to maintain very closesynchronisni between the distributors.

The various .tea-tures of the invention may be more clearly understood breference to the accompanying drawings 1n which Fig. l shows asynchronizing system employing the features of the invention and Figs.2, 3, 4 and 5 shoviT various modifications of 'the tuning circuitdisclosed in Fig. l.

Referring more particularly to Fig. l the synchronizin; equipment atstation A which is the controlling station includes a phonic wheel l0,which is driven by electrical impulses from the grounded source otenergy il, alternately connected. by means ot the lower leg of thetuning fork l2 to the elec tromagnets lil-*3 and lll-let. Mounted inclose proximity to one leg;n of the tuning fork is a polarizedelectroinagnet i5 in which an alternating; current is generated by thevibration ot the orlr. This elec de.: is connected the primary medir a ntransformer i6, the secondary winding or which is connected to the inputside of the amplifier ,Tl/l. The output side oii this amplitier isconnected to electromagnet l?, which is the driving magnet that keepsthe fork in vibration, the current through electroinagnet i9 heiniT inproper phase re lult;

liti:

lation, with respect to the movement of the fork. By means of thevariable capacity 20, the variable inductance 21 and the vari- -ableresistance 22, the circuit including these elements and electromagnet 15is tuned to a frequency within the range of possible operation ofthefork 12.

The phonic wheel 10 is employed to positively drive a rotatable brusharm 23 carrying a plurality of insulated brushes 24, 25 and 26 whichupon rotation of the switch arm are adapted to sweep over thedistributor segments. The distributor, a portion of which is showndeveloped, consists of a set of receiving segments 27 which aresuccessively connected to a receiving ring 28 by means of the brush 24,a set of Acorrecting segments 29 which are successively connected to thecorrecting ring 30 by means of brush 25; and a set of transmittingsegments 31 which are successively connected to the transmitting ring 32by means of the brush 26. The receiving segments are connected directlyto the magnets 33-33 of the printing mechanism and thc transmittingsegments are connected to the contacts of the printing transmitter 34.The correcting segments, of which there are twice as many as of thetransmitting or receixf'ing segments, are used only at the controlledstation but are preferably included in the apparatus at each station sothat, when desired, either station may be operated as the controlledstation. The transmitting ring 32 is connected dif'- ferentially to theline relay 35 andan artificial line is preferably provided, as shown, topermit duplex working over the system.

At station B which is the controlled station, the equipment is similarto that of station A, except that additional means is rovided forautomatically varying the tunlng of the oscillating circuit. The phonicwheel 10 is driven by the tuning fork 12' and the vibrations of thelatter cause the generation of an electromotive force in magnet 15resulting in the flow of an electrical current in the tuned circuit 15',21', 22', 16', 20 which is amplified and. passed through magnet 19',thus maintaining the tuning fork in vibration. "lhe phonic wheel 10' isdirectly connected to the brush arm 23' which in its rotation causesbrushes to sweep over a distributor consistin of receivingtcorrecting,and transmitting seglments, similar to `those of the distributor atstation A. The transmitting ring 32' is connected differentially to thewinding'of line relay 35' and the receiving ring 28' is connected to theupper contact of the line relay. The correcting segments are dividedinto two sets of alternate segments which are connected respectively tothe outer terlninals of correcting relay 36. Assuming the direction ofrotation of brush arm 2.- to be from right to left, the correctingrSegture of line relay 35' is connected to a grounded source of energy 41and the midoint of the winding of correcting relay 36 1s grounded. Theoperation of relay 36 serves to connect or disconnect the con denser 42in parallel with condenser 20 in the driving circuit of the tuning forkand thus change the tuning of the circuit.

In the operation of the system the tuning forks at therespective-stations are first set in vibration by hand. Since ltheoperation of these forks is similar, only that at station A will bcconsidered. The vibration of the fork 12 generates an electromotiveforce in the magnetized electromagnet 15 which produces an alternatingcurrent in the tuned circuit composed of the transformer 16, inductance21, and condenser 20. By means of the transformer the'voltage of thiscurrent is increased at the input terminals of the amplifier 17 which inturn produces a large lincrease in the current flowing throughtheelectromagnet 19. The phase` relations between the current inthegenerating magnet 15 and the drivingmagnet 19 are such that the currentgenerated tends to maintain the vibration of the fork, Awhich increasesits amplitude of vibration to a point where the energy dissipatedbecomesequal to the energizing force supplied, thus causing the fork to vibratesteadily at a given amplitude. The fork has a natural frequency ofvibration which changes slightly with amplitude, being slower for largeramplitudes and vice versa. If the circuit 15, 16, 20, 21, 22 is tuned bymeansof the inductance 21, resistance 22 and capacity 20 to a frequencywithin a certain frequency range which corresonds to a certain portionof the amplitu e range of -the fork and the suitable degree ofamplification provided, the fork will be maintained in vibration at -aconstant frequency and amplitude. The (method of maintaining the correcttuning-fof the circuit isf. as follows: Variable capacity 20 isdisconnected and variable inducta-nce 21 and variable resistance 22 areshort. circuited. The amplification is then increased until the forkvibrates freely. The inductance and resistance elements 21 and 22,respectively. are then increased in value until the amplitude ofvibration of the fork is lllaterially reduced. The variable capacity'any circuit w ich is sharply tuned.

denser 42 in parallel with condenser 20 of4 the tuning circuit.

In practice the operations occur in rapid succession and the receivingfork vibrates at a frequency intermediate the maximum and minlmum valuescoresponding to the change in the tuning circuit which is not oftenallouged to remain fixed for a time sufficient to stabilize the rate ofvibration of the fork at either extreme.

In the method describedabove the change of frequencyof the fork isproduced by detuning the tuned circuit by the addition of capaclty butit is of course obvious that the same result could also be obtained bychangingthe other constants of the circuit. i A igs. 2 to 5 show variousforms of tuned circuits which might be employed and which provide sharptuning. In Fig. 2 the circuit shown is the same as the system shown inFig. 1 consisting of the transformer 16 having a variable inductance 21and variableresistance 22 in the limary circuit-and a condenser in para]el with the secondary circuit andthe input terminals of the amplier 17.In Fig. 3 the fixed inductance 50 is connected in series with thesecondary Winding of 'transformer 16 and the variable condenser 20 isconnected across the input terminals of the amplifier. In Fig. 4 anautotransformer 51 is `employed with a fixed inductance in series withthe secondary windin and a condenser 20 'across the input teminas of,the-amplifier 17. In Fig. 5 an auto-transformer 51 is employed and aresistance 52 and finductance 53 connected in series with the primaryportion of the winding, while a variable condenser 20 is connected inparallel with the secondary' sortion of the winding`which is connectedirectly across the input terminals of the amplifier 17. Thesemodifications are shown to exemplify suitable circuits Which-may vbesharply tuned but; the invention is not limited to any particular tuningcircuit since satisfactory o eration may be obtained with What isclaimed is: 1. An isochronizing system comprising a distributor forimpartin impulses to a line, a vibrating mechanism or driving saiddistributor, a receiving distributor, a variable the transmittingdistributor to vary the tuning of said operating circuit whereby thedistributors are maintained in isochronism.

2. A synchronizing system comprising a distributor for impartin impulsesto a lme, a vibrating mechanism or driving said distributor, a receivingdistributor, a variable vibrating mechanism therefor having a sharplytuned operating circuit, and means cont-rolled by the line currentreversals and cooperating with the receiving distributor toautomatically alterI the tuning operating circuit whereby thedistributors are maintained in synchronism.

3. In a synchronizing system, a distributor for imparting electricalimpulses to a line, a second distributor for receiving said impulses, avibrating mechanism havin a sharply tuned operating circuit for drivingsaid receiving distributor, and means for altering the tuning of saidoperating circuit to -vary the frequency of vibration of the vibratingmechanism.

4. In a synchronizing system. means for controlling the transmission ofelectrical imulses to a line, means for receiving said lmpulses, avibrating mechanism havin a sharply tuned operating circuit for drivingsaid receiving means, and means for altering the tuning of the operatingcircuit to vary the frequency of vibration of the vibrating mechanism.

5. In a synchronizing system, a distributor for imparting electricalimpulses to a line, a vibrating ldevice for driving the distributor, asharply tuned operating circuit for operatin the vibrating device at apredetermined requency, a line relay operable by current impulsesreceived. over the line, a correcting relay, means dependent upon theoperation of the line relay fork imparting a 'current impulse to causethe operation of the correctin relay, a second distributor forvcontrolling te direction of o ration of the correcting relay, a'vibrating evice for driving said second distributor, a sharply tuned t econtrol of the correcting relay for detuning said circuit.

In witness whereofyI hereunto subscribe my name this 7th day`of June A..D., 1923.

AUSTEN M. CURTIS.

of said Y `o erating lcircuit therefor, and means under r

